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    <title>Togl Tcl API</title>
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    <h1 align="center">Togl Tcl API</h1>

    <h2>Contents</h2>
    <ul>
      <li><a href="#tclfuncs">Togl Tcl command</a>
      <li><a href="#toglfuncs">Togl widget commands</a>
      <ul>
	<li><a href="#configuration">Configuration Commands</a>
	<li><a href="#extensions">Extensions Command</a>
	<li><a href="#rendering">Rendering Commands</a>
	<li><a href="#image">Image Commands</a>
	<li><a href="#font">Font Commands</a>
	<li><a href="#overlay">Overlay Commands</a>
	<li><a href="#stereo cmds">OpenGL (Stereo) Commands</a>
      </ul>
      <li><a href="#options">Togl configuration options</a>
      <ul>
	<li><a href="#drawing">Drawing callbacks</a>
	<li><a href="#geometry">Geometry Options</a>
	<li><a href="#timer">Timer Options</a>
	<li><a href="#stereo options">Stereo Options</a>
	<li><a href="#miscellaneous">Miscellaneous Options</a>
	<li><a href="#pixelformat">Pixel Format Options</a>
      </ul>
    </ul>

    <hr>

    <h2><a name="tclfuncs">Togl Tcl command</a></h2>

    <p>
    The togl command creates a new Tk widget, a Tcl command,
    whose name is <var>pathName</var>.
    This command may be used to invoke various operations on the widget.
    <blockquote>
      <code>togl <var>pathName</var> [<a href="#options">options</a>]</code>
    </blockquote>
    If no options are given, a 400 by 400 pixel RGB window is created.
    This command may be used to invoke various operations on the widget.

    <h2><a name="toglfuncs">Togl widget commands</a></h2>

    The following commands are possible for an existing togl widget:

    <h3><a name="configuration">Configuration commands</a></h3>

    <dl>
      <dt><code><var>pathName</var> cget <var>-option</var></code>
      <dd>
      Return current value of given configuration option.
    </dl>

    <dl>
      <dt>
      <code><var>pathName</var> configure</code><br>
      <code><var>pathName</var> configure <var>-option</var></code>
      <dd>
      If no <var>option</var> is given,
      then return information about
      all configuration <a href="#options">options</a>.
      Otherwise,
      return configuration information for given <var>option</var>.
      All configuration information consists of five values:
      the configuration option name,
      the option database name,
      the option database class,
      the default value,
      and the current value.
    </dl>

    <dl>
      <dt><code><var>pathName</var> configure <var>-option</var> <var>value</var></code>
      <dd>
      Reconfigure a Togl widget.
      <var>option</var> may be any one of the options listed below.
    </dl>

    <dl>
      <dt><code><var>pathName</var> contexttag</code>
      <dd>
      Returns an integer that represents the context tag.
      All Togl widgets with the same context tag share display lists.
    </dl>

    <h3><a name="extensions">Extensions command</a></h3>

    <dl>
      <dt><code><var>pathName</var> extensions</code>
      <dd>
      Returns a list of OpenGL extensions available.  For example:
      <blockquote><pre><code>
if {[lsearch [<i>pathName</i> extensions] GL_EXT_bgra] != -1]} {
    ....
}
</code></pre></blockquote>
      would check if the GL_EXT_bgra extension were supported.
    </dl>

    <h3><a name="rendering">Rendering commands</a></h3>

    <dl>
      <dt><code><var>pathName</var> postredisplay</code>
      <dd>
      Cause the displaycommand callback to be called
      the next time the event loop is idle.
    </dl>

    <dl>
      <dt><code><var>pathName</var> render</code>
      <dd>
      Causes the displaycommand callback to be called for <var>pathName</var>.
    </dl>

    <dl>
      <dt><code><var>pathName</var> swapbuffers</code>
      <dd>
      Causes front/back buffers to be swapped if in double buffer mode.
      And flushs the OpenGL command buffer if in single buffer mode.
      (So this is appropriate to call after every frame is drawn.)
    </dl>

    <dl>
      <dt><code><var>pathName</var> makecurrent</code>
      <dd>
      Make the widget specified by <var>pathName</var> and its OpenGL context
      the current ones.
      This is implicitly called before any callback command is invoked.
    </dl>

    <dl>
      <dt><code><var>pathName</var> copycontextto <var>toPathName</var> <var>mask</var></code>
      <dd>
      Copy a subset of the OpenGL context state from <var>pathName</var> to
      <var>toPathName</var> according the given mask.
      The mask is an integer corresponding to the same values as
      <a href="http://www.opengl.org/sdk/docs/man/xhtml/glPushAttrib.xml">
	glPushAttrib</a>.
    </dl>

    <h3><a name="image">Image commands</a></h3>

    <dl>
      <dt><code><var>pathName</var> takephoto <var>imagename</var></code>
      <dd>
      Copy the contents of the togl window into the given Tk photo image.
      Transparency values are copied and should be fully opaque for windows
      without alpha bitplanes.
    </dl>

    <h3><a name="font">Font commands</a></h3>

    <p>
    These functions provide an interface to the simple bitmap font capabilities
    that every OpenGL implementation provides.
    Better font support is found in other packages, <i>e.g.</i>,
    <a href="http://www.tcl3d.org/">Tcl3D</a>
    or with different <a href="capi.html#font">C APIs</a>.

    <dl>
      <dt><code><var>pathName</var> loadbitmapfont <var>font</var></code>
      <dd>
      <var>font</var> can be any of font descriptions listed in the Tk
      <a href="http://www.tcl.tk/man/tcl8.4/TkCmd/font.htm#M13">font</a> command.
      It returns a togl font object.
    </dl>

    <dl>
      <dt><code><var>pathName</var> unloadbitmapfont <var>toglfont</var></code>
      <dd>
      Releases the OpenGL resources needed by the <var>toglfont</var>.
    </dl>

    <dl>
      <dt><code><var>pathName</var> write <var>toglfont</var> [-pos <var>xyzw</var>] [-color <var>rgba</var>] <var>string</var></code>
      <dd>
      Write the given <var>string</var> in the given <var>toglfont</var>,
      optionally at a particular position, <var>xyzw</var>
      and color, <var>rgba</var>.
      <var>xyzw</var> is either a 2, 3, or 4 element list of numbers.
      <var>rgba</var> is either a 3 or 4 element list of numbers.
    </dl>

    <h3><a name="overlay">Overlay Commands</a></h3>

    <dl>
      <dt><code><var>pathName</var> uselayer <var>layer</var></code>
      <dd>
      This is a variation on the <code>makecurrent</code> command
      that makes the overlay OpenGL context current
      if <var>layer</var> is 2
      and makes the normal OpenGL context current
      if <var>layer</var> is 1.
    </dl>

    <dl>
      <dt><code><var>pathName</var> showoverlay</code>
      <dd>
      Turn on drawing in the overlay planes.
    </dl>

    <dl>
      <dt><code><var>pathName</var> hideoverlay</code>
      <dd>
      Turn off drawing in the overlay planes.
    </dl>

    <dl>
      <dt><code><var>pathName</var> postredisplayoverlay</code>
      <dd>
      Cause the overlay OpenGL context to be redrawn the next time
      the Tcl event loop is idle.
    </dl>

    <dl>
      <dt><code><var>pathName</var> renderoverlay</code>
      <dd>
      Causes the overlaydisplaycommand callback to be called for <var>pathName</var>.
    </dl>

    <dl>
      <dt><code><var>pathName</var> existsoverlay</code>
      <dd>
      Return true if togl widget has overlay planes.
    </dl>

    <dl>
      <dt><code><var>pathName</var> ismappedoverlay</code>
      <dd>
      Return true if overlay planes are shown.
    </dl>

    <dl>
      <dt><code><var>pathName</var> getoverlaytransparentvalue</code>
      <dd>
      Return overlay plane's transparent pixel value.
    </dl>

    <h3><a name="stereo cmds">OpenGL (Stereo) Commands</a></h3>
    These commands exist to support stereo rendering.
    Just replace select OpenGL calls with the Togl versions
    and stereo rendering will magically work.  And don't forget
    to update the <a href="#stereo options">stereo options</a>.

    <dl>
      <dt><code><var>pathName</var> drawbuffer <var>mode</var></code>
      <dd>
      Replaces calls to
      <a href="http://www.opengl.org/sdk/docs/man/xhtml/glDrawBuffer.xml">
	glDrawBuffer</a>.
      The mode is an integer.
    </dl>

    <dl>
      <dt><code><var>pathName</var> clear <var>mask</var></code>
      <dd>
      Replaces calls to
      <a href="http://www.opengl.org/sdk/docs/man/xhtml/glClear.xml">
	glClear</a>.
      The mask is an integer.
    </dl>

    <dl>
      <dt><code><var>pathName</var> frustum <var>left right bottom top near far</var></code>
      <dd>
      Replaces calls to
      <a href="http://www.opengl.org/sdk/docs/man/xhtml/glFrustum.xml">
	glFrustum</a>.
    </dl>

    <dl>
      <dt><code><var>pathName</var> ortho <var>left right bottom top near far</var></code>
      <dd>
      Replaces calls to
      <a href="http://www.opengl.org/sdk/docs/man/xhtml/glOrtho.xml">
	glOrtho</a>.
    </dl>

    <dl>
      <dt><code><var>pathName</var> numeyes</code>
      <dd>
      Returns numbers of eyes &mdash; basically,
      2 for stereo views and 1 for all others,
      except some stereo views only need one eye from OpenGL.
    </dl>

    <h2><a name="options">Togl configuration options</a></h2>

    Togl's configuration options can be separated into several categories:
    geometry, pixel format, and other.
    The pixel format related options can only be set at widget creation time.
    The other options can be changed dynamically
    by the <code><var>pathName</var> configure</code> command (see above).

    <h3><a name="drawing">Drawing callbacks</a></h3>

    <table border="0">
      <thead>
	<tr valign="top">
	  <th>Option</th>
	  <th>Default</th>
	  <th>Comments</th>
	</tr>
      </thead>
      <tbody>
	<tr valign="top">
	  <td><code>-createcommand</code></td>
	  <td align="center">{}</td>
	  <td>
	    Can be abbreviated <code>-create</code>.
	  </td>
	</tr>
	<tr valign="top">
	  <td><code>-displaycommand</code></td>
	  <td align="center">{}</td>
	  <td>
	    Can be abbreviated <code>-display</code>.
	  </td>
	</tr>
	<tr valign="top">
	  <td><code>-reshapecommand</code></td>
	  <td align="center">{}</td>
	  <td>
	    Can be abbreviated <code>-reshape</code>.
	  </td>
	</tr>
	<tr valign="top">
	  <td><code>-destroycommand</code></td>
	  <td align="center">{}</td>
	  <td>
	    Can be abbreviated <code>-destroy</code>.
	  </td>
	</tr>
	<tr valign="top">
	  <td><code>-overlaydisplaycommand</code></td>
	  <td align="center">{}</td>
	  <td>
	    Can be abbreviated <code>-overlaydisplay</code>.
	  </td>
	</tr>
      </tbody>
    </table>

    <h3><a name="geometry">Geometry Options</a></h3>

    <table border="0">
      <thead>
	<tr valign="top">
	  <th>Option</th>
	  <th>Default</th>
	  <th>Comments</th>
	</tr>
      </thead>
      <tbody>
	<tr valign="top">
	  <td><code>-width</code></td>
	  <td align="center">400</td>
	  <td>
	    Set width of widget in pixels.
	    It may have any of the forms accepted by <b>Tk_GetPixels</b>.
	  </td>
	</tr>
	<tr valign="top">
	  <td><code>-height</code></td>
	  <td align="center">400</td>
	  <td>
	    Set height of widget in pixels.
	    It may have any of the forms accepted by <b>Tk_GetPixels</b>(3).
	  </td>
	</tr>
	<tr valign="top">
	  <td><code>-setgrid</code></td>
	  <td align="center">0</td>
	  <td>
	    Turn on gridded geometry management for togl widget's toplevel
	    window and specify the geometry of the grid.
	    See the manual pages for Tk's <b>wm</b>(n) and <b>Tk_SetGrid</b>(3)
	    for more information.
	    Unlike the <b>text</b> widget,
	    the same value is used for both width and height increments.
	  </td>
	</tr>
      </tbody>
    </table>

    <h3><a name="timer">Timer Options</a></h3>

    <table>
      <thead>
	<tr valign="top">
	  <th>Option</th>
	  <th>Default</th>
	  <th>Comments</th>
	</tr>
      </thead>
      <tbody>
	<tr valign="top">
	  <td><code>-time</code></td>
	  <td align="center">1</td>
	  <td>
	    Specifies the interval, in milliseconds, for
	    calling the timer callback function which
	    was registered with -timercommand.</td>
	</tr>
	<tr valign="top">
	  <td><code>-timercommand</code></td>
	  <td align="center">{}</td>
	  <td>
	    Can be abbreviated <code>-timer</code>.
	  </td>
	</tr>
      </tbody>
    </table>

    <h3><a name="stereo options">Stereo Options</a></h3>

    <table>
      <thead>
	<tr valign="top">
	  <th>Option</th>
	  <th>Default</th>
	  <th>Comments</th>
	</tr>
      </thead>
      <tbody>
	<tr valign="top">
	  <td><code>-eyeseparation</code></td>
	  <td align="center">2.0</td>
	  <td>
	    Set the distance between the eyes in viewing coordinates.
	  </td>
	</tr>

	<tr valign="top">
	  <td><code>-convergence</code></td>
	  <td align="center">30.0</td>
	  <td>
	    Set the distance to the screen from the eye in viewing coordinates
	    (the distance at which the eyes converge).
	  </td>
	</tr>
      </tbody>
    </table>

    <blockquote>
      You'd think these values would be given in physical units,
      but there's no single right way to convert to viewing coordinates
      from physical units.
      So if you're willing to use Tk's idea of the horizontal size of a
      window in millimeters (not always correct),
      you could convert the average eye separation of 63 mm
      to your viewing coordinates, and use that value as the eye separation.
    </blockquote>

    <h3><a name="miscellaneous">Miscellaneous Options</a></h3>

    <table>
      <thead>
	<tr valign="top">
	  <th>Option</th>
	  <th>Default</th>
	  <th>Comments</th>
	</tr>
      </thead>
      <tbody>
	<tr valign="top">
	  <td><code>-cursor</code></td>
	  <td align="center">""</td>
	  <td>
	    Set the cursor in the widget window.
	  </td>
	</tr>

	<tr valign="top">
	  <td><code>-swapinterval</code></td>
	  <td align="center">1</td>
	  <td>
	    Set the minimum swap interval measure in video frame periods.
	    The default is 1 for for non-tearing artifacts
	    when swapping buffers.
	    Use a value of 0 when benchmarking frame rates.
	  </td>
	</tr>

	<tr valign="top">
	  <td><code>-ident</code></td>
	  <td align="center">""</td>
	  <td>
	    A user identification string.  This is used match widgets
	    for the <code>-sharecontext</code>
	    and the <code>-sharelist</code> options (see below).
	    This is also useful in your callback functions
	    to determine which Togl widget is the caller.
	  </td>
	</tr>
      </tbody>
    </table>

    <h3><a name="pixelformat">Pixel Format Options</a></h3>

    The following options can only be given when the togl widget is created
    &mdash; that is, unlike other options,
    the togl widget can not be reconfigured with different values
    for the following options after it is created.

    <table border="0">
      <thead>
	<tr valign="top">
	  <th>Option</th>
	  <th>Default</th>
	  <th>Comments</th>
	</tr>
      </thead>
      <tbody>
	<tr valign="top">
	  <td><code>-rgba</code></td>
	  <td align="center">true</td>
	  <td>If true, use RGB(A) mode, otherwise use Color Index mode.</td>
	</tr>
	<tr valign="top">
	  <td><code>-redsize</code></td>
	  <td align="center">1</td>
	  <td>Minimum number of bits in red component.</td>
	</tr>
	<tr valign="top">
	  <td nowrap="nowrap"><code>-greensize</code></td>
	  <td align="center">1</td>
	  <td>Minimum number of bits in green component.</td>
	</tr>
	<tr valign="top">
	  <td><code>-bluesize</code></td>
	  <td align="center">1</td>
	  <td>Minimum number of bits in blue component.</td>
	</tr>
	<tr valign="top">
	  <td><code>-alpha</code></td>
	  <td align="center">1</td>
	  <td>
	    If true and <code>-rgba</code> is true, request an alpha channel.
	  </td>
	</tr>
	<tr valign="top">
	  <td><code>-alphasize</code></td>
	  <td align="center">1</td>
	  <td>Minimum number of bits in alpha component.</td>
	</tr>

	<tr><td colspan="3">&nbsp;</td></tr>
	<tr valign="top">
	  <td><code>-double</code></td>
	  <td align="center">false</td>
	  <td>
	    If true, request a double-buffered window, otherwise
	    request a single-buffered window.
	  </td>
	</tr>

	<tr><td colspan="3">&nbsp;</td></tr>
	<tr valign="top">
	  <td><code>-depth</code></td>
	  <td align="center">false</td>
	  <td>If true, request a depth buffer.</td>
	</tr>
	<tr valign="top">
	  <td><code>-depthsize</code></td>
	  <td align="center">1</td>
	  <td>Minimum number of bits in depth buffer.</td>
	</tr>

	<tr><td colspan="3">&nbsp;</td></tr>
	<tr valign="top">
	  <td><code>-accum</code></td>
	  <td align="center">false</td>
	  <td>If true, request an accumulation buffer.</td>
	</tr>
	<tr valign="top">
	  <td><code>-accumredsize</code></td>
	  <td align="center">1</td>
	  <td>Minimum number of bits in accumulation buffer red component.</td>
	</tr>
	<tr valign="top">
	  <td nowrap="nowrap"><code>-accumgreensize</code></td>
	  <td align="center">1</td>
	  <td>
	    Minimum number of bits in accumulation buffer green component.
	  </td>
	</tr>
	<tr valign="top">
	  <td><code>-accumbluesize</code></td>
	  <td align="center">1</td>
	  <td>Minimum number of bits in accumulation buffer blue component.</td>
	</tr>
	<tr valign="top">
	  <td><code>-accumalphasize</code></td>
	  <td align="center">1</td>
	  <td>
	    Minimum number of bits in accumulation buffer alpha component.
	  </td>
	</tr>

	<tr><td colspan="3">&nbsp;</td></tr>
	<tr valign="top">
	  <td><code>-stencil</code></td>
	  <td align="center">false</td>
	  <td>If true, request a stencil buffer.</td>
	</tr>
	<tr valign="top">
	  <td><code>-stencilsize</code></td>
	  <td align="center">1</td>
	  <td>Minimum number of bits in stencil component.</td>
	</tr>

	<tr><td colspan="3">&nbsp;</td></tr>
	<tr valign="top">
	  <td><code>-auxbuffers</code></td>
	  <td align="center">0</td>
	  <td>Desired number of auxiliary buffers.</td>
	</tr>

	<tr><td colspan="3">&nbsp;</td></tr>
	<tr valign="top">
	  <td><code>-privatecmap</code></td>
	  <td align="center">false</td>
	  <td>
	    Only applicable in color index mode.
	    If false, use a shared read-only colormap.
	    If true, use a private read/write colormap.
	  </td>
	</tr>

	<tr><td colspan="3">&nbsp;</td></tr>
	<tr valign="top">
	  <td><code>-overlay</code></td>
	  <td align="center">false</td>
	  <td>If true, request overlay planes.</td>
	</tr>

	<tr><td colspan="3">&nbsp;</td></tr>
	<tr valign="top">
	  <td><code>-stereo</code></td>
	  <td align="center">mode</td>
	  <td>
	    See the <a href="stereo.html">stereo</a> information
	    for details about the various modes.
	    Stereo parameters are changed with the
	    <a href="#stereo options">stereo options</a>.
	    <p>
	    When using a non-native stereo mode, the OpenGL
	    <a href="http://www.opengl.org/sdk/docs/man/xhtml/glDrawBuffer.xml">
	      glDrawBuffer</a>,
	    <a href="http://www.opengl.org/sdk/docs/man/xhtml/glClear.xml">
	      glClear</a>,
	    <a href="http://www.opengl.org/sdk/docs/man/xhtml/glFrustum.xml">
	      glFrustum</a>, and
	    <a href="http://www.opengl.org/sdk/docs/man/xhtml/glOrtho.xml">
	      glOrtho</a> calls
	    must be replaced with the Togl
	    <a href="#stereo cmds">Tcl</a> or
	    <a href="capi.html#stereo">C</a> versions.
	  </td>
	</tr>

	<tr><td colspan="3" height="0">&nbsp;</td></tr>
	<tr valign="top">
	  <td><code>-pbuffer</code></td>
	  <td align="center">false</td>
	  <td>
	    If true, request off-screen framebuffer memory for the graphics.
	    The resulting togl widget should not be managed.
	  </td>
	</tr>
	<tr>
	  <td><code>-largestpbuffer</code></td>
	  <td align="center">false</td>
	  <td>
	    If true, when asking for a pbuffer of a given size
	    and there isn't enough framebuffer memory available,
	    fallback to the largest size available.
	  </td>
	</tr>

	<tr><td colspan="3" height="0">&nbsp;</td></tr>
	<tr valign="top">
	  <td><code>-multisample</code></td>
	  <td align="center">false</td>
	  <td>
	    If true, request an multisampled rendering context.
	  </td>
	</tr>

	<!--
	<tr valign="top">
	  <td><code>-fullscreen</code></td>
	  <td align="center">false</td>
	  <td>
	    If true, request an multisampled rendering context.
	    <em>Requires Tcl/Tk 8.5 or newer on UNIX and Microsoft Windows platforms.</em>
	  </td>
	</tr>
	-->

	<tr valign="top">
	  <td><code>-indirect</code></td>
	  <td align="center">false</td>
	  <td>
	    If present, request an indirect rendering context.
	    A direct rendering context is normally requested.
	    <em>Only significant on Unix/X11.</em>
	  </td>
	</tr>

	<tr valign="top">
	  <td><code>-sharelist</code></td>
	  <td align="center">""</td>
	  <td>
	    Togl identification string or window path name
	    of an existing Togl widget with which to share display lists.
	    If it is not possible to share display lists
	    between the two togl widgets
	    (depends on the graphics driver and the particular formats),
	    it fails.
	  </td>
	</tr>
	<tr valign="top">
	  <td><code>-sharecontext</code></td>
	  <td align="center">""</td>
	  <td>
	    Togl identification string or window path name
	    of an existing Togl widget with which to share the OpenGL context.
	    <i>Note:  all other pixel format options are ignored.</i>
	  </td>
	</tr>
	<tr valign="top">
	  <td><code>-pixelformat</code></td>
	  <td align="center">0</td>
	  <td>
	    Set the pixel format to the (platform-dependent) given value.
	    This is a backdoor into choosing a particular pixel format
	    that was determined by other means.
	  </td>
	</tr>
      </tbody>
    </table>

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